Lyme disease is the most common arthropod-borne infection in the United States, with almost 10,000 cases diagnosed annually. Borrelia burgdorferi, a bacterium in the spirochete phylum, is the causative agent of Lyme disease in North America. The B. burgdorferi genome is atypical for a bacterium: it is composed of both linear and circular DNA molecules. Research in the laboratory have been able to demonstrate that extracellular components of B. burgdorferi 1) appear to be present wherever active growth of the organism is taking place and therefore, may be useful as a diagnostic indicator of active infection and/or treatment effectiveness; 2) are involved in the packaging and protection of intact DNA molecules containing a few known and many unknown genes and gene products; 3) appear to specifically interact with immunoglobulin M molecules in a unique fashion, perhaps to escape immune surveillance, and 4) possesses potent, non-specific mitogenic activity in outer surface proteins A, B and C which may cause an inappropriate and non-effective stimulation of the immune system triggering some disease components. Using a modification of the capture/detection method, researchers have achieved improved isolation and culture of the microorganism with fewer contaminants. Researchers in this group continue to examine these and other bioproducts with the aim of improving the prevention, treatment and diagnosis of Lyme disease.